What you'll need

1. Pipes

There is an ongoing war about PVC vs other pipes. The most important factor is that the pipes need to be food safe. Many PVC pipes are not, but even those who are might leak toxic material over the years (especially if exposed to the sun).
To be safe we decided to use high temperature polypropylene (PP) Pipes which can be used in temperatures up to 90°C (194°F) and still won't leak any toxics. They're still pretty cheap.

Cost: 23.19€

2. A frame

Cost: 5,94€

3. Destilled or rain water

Since we can't collect the rain water, we bought 3x 5l distilled water from our local hardware shop. Distilled water is better for hydroponic systems than tap water because the minerals from the tap water can clog the small roots and ultimately kill the plants.

It doesn't matter that the cups don't reach the bottom of the pipe since the plants will already have longer roots when they get in the tubes. If you don't plan to pre-treat them, you can build small dams, use bigger cups, smaller pipes or use small ropes as you'll see later.